Wind turbine blades sending false images to weather station

WOODSTOCK, Maine — An apparent intense snow squall that appeared on National Weather Service radar maps over Woodstock on Thursday night was nothing more than radar pulse from the weather station in Gray bouncing off wind turbines on Spruce Mountain.

Although many in Oxford County saw a brief snow squall late Thursday evening that left a dusting on the roads, National Weather Service weather radar maps showed intense snow squalls in a small areas. The sites coincided with wind turbines, such as the 10 on Spruce Mountain and 28 on Mars Hill in Aroostook County.

“It’s an issue nationwide with all sorts of wind farms,” said Margaret Curtis, a meteorologist with the National Weather Service in Gray.

The problem, she said, is that the radar pulse sent out from Gray that is meant to bounce off raindrops also bounces off mountains and turbines.

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The radar is sending out 300 to 1,300 pulses per second, which means it can sometimes pick up migrations of birds on a clear day that show up as weather phenomena on the map.

The meteorologists can easily distinguish whether a stationary mountain is causing what they call “ground clutter,” but it is sometimes a little more difficult with moving targets such as wind turbines until they know their exact location, she said.

Once they realize the cause of the disturbance, the weather patches could be filtered out by repositioning the radar higher.